The present invention relates to human-computer interfaces. In particular, the present invention relates to computer input devices.
In computer systems, many tasks such as navigation, three-dimensional object manipulation, and image editing can require multiple degrees of freedom (DOF) of rotation, zooming, or translation. Conventional mice, however, allow integrated control of only two degrees of freedom at any one time. While three dimensional/six degree of freedom input devices are available, such devices are difficult to use for standard two-dimensional cursor control. In the prior art, some mice have been augmented with wheels or joysticks for added degrees of freedom, but typically these controls are dedicated to secondary tasks such as scrolling or panning. Thus, all prior art input devices have limitations in a workflow that may frequently switch between two-dimensional pointing tasks and multi-degrees of freedom manipulations. Input devices and interaction techniques that can enhance the directness and degree of manipulation possible in such a workflow are therefore needed.
In the prior art, there are several multi-degree of freedom input devices available. However, each of these devices requires expensive orientation detection systems in order to detect the position and orientation of the mouse. In particular, most of these systems require a magnetic field generated by an active tablet or other magnetic source. Position and orientation information is detected by a magnetic sensor (typically in the form of one or more magnetic coils) which is embedded in the input device. For example, one input device being sold as the “Intuos 4D Mouse” from Wacom uses a tablet-based rotation-sensing puck. Other magnetic six degree-of-freedom input devices include the Polhemus Fastrak and the Ascension Flock of Birds, which have been used for six degrees of freedom input on an ActiveDesk display surface. Still other devices provide four degrees of freedom using an active sensing tablet that measures the (x, y) position of the device as well as the degree to which the device is tilted forward-back or left-right.
In all cases where an active sensing tablet or a magnetic field source/sensor pair is used to sense the orientation of the input device, the input device is very expensive. As such, an input device that can sense its orientation without expensive sensing equipment is needed.
The prior art also includes a two-ball mouse, which senses changes in rotation about its vertical axis. However this mouse is only able to sense three degrees of freedom and cannot measure absolute rotation of the mouse, only changes in the rotation of the mouse. One reference of the prior art has suggested combining the two-ball mouse with the tablet-based tilt-sensing mouse to produce a five-degree of freedom mouse. However, this combination would still result in an expensive tablet-based mouse.